.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.TH SCALB 3 2016-03-15 "" "Linux Programmer's Manual"
.SH NAME
scalb, scalbf, scalbl \- multiply floating-point number
by integral power of radix (OBSOLETE)
.SH SYNOPSIS
.B #include <math.h>
.sp
.BI "double scalb(double " x ", double " exp );
.br
.BI "float scalbf(float " x ", float " exp );
.br
.BI "long double scalbl(long double " x ", long double " exp );
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR scalb ():
.RS 4
_XOPEN_SOURCE\ >=\ 500
.\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.RE
.br
.BR scalbf (),
.BR scalbl ():
.RS 4
_XOPEN_SOURCE\ >=\ 600
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.RE
.ad b
.SH DESCRIPTION
These functions multiply their first argument
.I x
by
.B FLT_RADIX
(probably 2)
to the power of
.IR exp ,
that is:
.nf

    x * FLT_RADIX ** exp
.fi

The definition of
.B FLT_RADIX
can be obtained by including
.IR <float.h> .
.\" not in /usr/include but in a gcc lib
.SH RETURN VALUE
On success, these functions return
.IR x
*
.B FLT_RADIX
**
.IR exp .

If
.I x
or
.I exp
is a NaN, a NaN is returned.

If
.I x
is positive infinity (negative infinity),
and
.I exp
is not negative infinity,
positive infinity (negative infinity) is returned.

If
.I x
is +0 (\-0), and
.I exp
is not positive infinity, +0 (\-0) is returned.

If
.I x
is zero, and
.I exp
is positive infinity,
a domain error occurs, and
a NaN is returned.

If
.I x
is an infinity,
and
.I exp
is negative infinity,
a domain error occurs, and
a NaN is returned.

If the result overflows,
a range error occurs,
and the functions return
.BR HUGE_VAL ,
.BR HUGE_VALF ,
or
.BR HUGE_VALL ,
respectively, with a sign the same as
.IR x .

If the result underflows,
a range error occurs,
and the functions return zero, with a sign the same as
.IR x .
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
and the other argument is not a NaN
.\" .I errno
.\" is set to
.\" .BR EDOM .
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
.TP
Range error, overflow
.\" .I errno
.\" is set to
.\" .BR ERANGE .
An overflow floating-point exception
.RB ( FE_OVERFLOW )
is raised.
.TP
Range error, underflow
.\" .I errno
.\" is set to
.\" .BR ERANGE .
An underflow floating-point exception
.RB ( FE_UNDERFLOW )
is raised.
.PP
These functions do not set
.IR errno .
.\" FIXME . Is it intentional that these functions do not set errno?
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6803
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6804
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw28 lb lb
l l l.
Interface	Attribute	Value
T{
.BR scalb (),
.BR scalbf (),
.BR scalbl ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
.BR scalb ()
is specified in POSIX.1-2001, but marked obsolescent.
POSIX.1-2008 removes the specification of
.BR scalb (),
recommending the use of
.BR scalbln (3),
.BR scalblnf (3),
or
.BR scalblnl (3)
instead.
The
.BR scalb ()
function is from 4.3BSD.

.BR scalbf ()
and
.BR scalbl ()
are unstandardized;
.BR scalbf ()
is nevertheless present on several other systems
.\" Looking at header files: scalbf() is present on the
.\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
.SH SEE ALSO
.BR ldexp (3),
.BR scalbln (3)
